Barrier operator system

ABSTRACT

A barrier operator moves a movable barrier using a motive source having a movable member, a station, and first and second flexible members. The station includes a drive system operatively coupled to the movable member of the motive source. The drive system includes input and output members. The first and second flexible members each have first and second ends and a portion extending from the station. The first ends of each flexible members are operatively coupled to the movable barrier and the second ends of each of the flexible members are operatively coupled to the output drive system member of the station. Aspects include the first and second flexible members being cable or wire. Other aspects include the output drive system member of the station being a spool. The drive system further includes a gear box operatively coupled to the spool. Other aspects include the movable barrier being a gate or door. Further aspects include the motive member being a 3-phase alternate current electric motor having a motor shaft as the movable member. The electric motor is supplied with 3-phase electrical power having voltage levels less than 65 volts root mean square. Additional aspects include calibration of fully opened and closed positions of the movable barrier, automatically positioning of the movable barrier by the barrier operator, supplying 0 hertz electrical power to the electric motor for heating based upon a temperature threshold, and control of frequency of the electrical power supplied to the motor based according to a continuous function of barrier position.

TECHNICAL FIELD

The present invention relates generally to barrier systems, and moreparticularly, to barrier operators. The present invention is related tocommonly assigned, concurrently filed and co-pending U.S. ApplicationSer. No. 09/238,697 for "Barrier Operator System."

BACKGROUND OF THE INVENTION

Barriers of all types are used throughout the world to prevent intrusioninto restricted areas or retain personnel or goods within restrictedareas. Intruders include unwanted personnel, animals, vehicles, and theweather. At times personnel and goods must enter or leave restrictedareas, resulting in the requirement for at least part of the barrier tobe movable. Movable barriers, such as gates, doors, and movable portionsof walls, allow passage out of and into restricted areas. Humans havebeen used to move movable barriers. In many areas of the world theystill do. However, barrier operators have been developed to replace theneed for humans to supply the motive force needed to move movablebarriers.

Barrier operators are abundant and diverse in design, and available frommany manufacturers. These barrier operators typically utilize commonelements. One common element is a chain or rail that mechanicallyinterfaces with a motive source that supplies the motive force to movethe movable barriers. Due to the inherent nature of these chain and railsystems, requirements for the motive source are demanding. The chain andrail systems are heavy and maintenance intensive, generate greatfrictional drag, are vulnerable to weather conditions, require specialinstallation skills, and demand extra reinforcement of barriers tohandle stresses inherent with the systems.

The motive sources typically used with barrier operators generally areelectrical motors. These motors typically are either DC, or high voltagesingle phase or three phase AC. Unfortunately, these motors haveassociated issues that adversely affect barrier operators. For instance,the DC motors tend to be short lived and have high maintenancerequirements. The single phased and three phase high voltage AC motorsrequire local connections to high voltage, electrical power sourceshaving voltage ratings such as 115, 230, or 460 volts with associateddanger introduced to the region of the barrier operators. Also, controlby prior art barrier operators of barriers is limited resulting in poorperformance in positioning the barrier, and accelerating or deceleratingthe barrier.

Prior art barrier operators have also performed poorly under emergencyconditions. For instance, deaths have resulted due to emergency medicalpersonnel being unable to move barriers because the medical personneldid not have access codes or the primary source of power for a barrieroperator failed.

Providing power to barrier operators has created logistical problems aswell. The expense of running a power line to the barrier operator orusing elaborate remote based power systems are common problems. Anothercommon problem arises from the harsh environments inflicted on somebarrier operators. These environments include extreme cold requiringadded equipment to maintain an environment suitable for operation.

Attempts have been made to remedy some problems with barrier operators.However, these attempts have been impractical or have been limited tospecialized applications. A solution to the multifaceted problemsinvolved with barrier operators which can be applied to broad classes ofbarriers has been absent from prior art barrier operators. The presentinvention fulfills these needs and further provides other relatedadvantages.

SUMMARY OF THE INVENTION

The present invention resides in a barrier operator to move a movablebarrier. The barrier operator includes a motive source having a movablemember, a station, and first and second flexible members. The stationincludes a drive system having an input member and an output member. Theinput drive system member is coupled to the movable member of the motivesource.

The first and second flexible members each have first and second endsand a portion extending a length from the station. The first ends of theflexible members are operatively coupled to the movable barrier. Thesecond ends of the flexible members are operatively coupled to theoutput drive system member of the of the station. The length of one ofthe extending portions of the first and second flexible members becomesshorter and the length of the other of the extending portions of thefirst and second flexible members becomes longer as the movable memberof the motive source moves to move the movable barrier.

Further aspects of the barrier operator include the first and secondflexible members comprising cable, rope, strand, string, chain, flexibletubing, or filament. Other aspects of the barrier operator include theflexible members being made of synthetics, natural material, or metal.Further aspects of the barrier operator include the output drive systemmember of the station comprising a spool. The drive system of thestation further comprises a gear box operatively coupled to the spool.Furthermore, the gear box is operatively coupled to a first pulley. Thefirst pulley is operatively coupled to a belt and the belt isoperatively coupled to a second pulley. The second pulley is operativelycoupled to the movable member of the motive source. Other aspects havethe drive system of the station comprise a worm operatively coupled to aworm wheel. Further aspects include the barrier operator comprisingeither a gate or a door.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a barrier operator in accordancewith the present invention attached to a movable barrier in a typicaloperating environment.

FIG. 2 is an enlarged perspective view of the barrier operator of FIG. 1attached to a movable barrier.

FIG. 3 is an enlarged, perspective view of the barrier operator of FIG.2 attached to a movable barrier.

FIG. 4 is another enlarged, perspective view of the barrier operator ofFIG. 2.

FIG. 5 is a sectional view of a gear box of the barrier operator of FIG.4 used to transmit rotational force between a motor and a winch spool.

FIG. 6 is a schematic drawing of electrical power and electronic controlsystems of the barrier operator of FIG. 4.

FIG. 7 is a flowchart of a method used for position calibration.

FIG. 8 is a flowchart of a method used in controlling travel of themovable barrier.

DETAILED DESCRIPTION OF THE INVENTION

As shown in the drawings for purposes of illustration, the presentinvention is embodied in a barrier operator indicated generally byreference 10. In a depicted embodiment, the barrier operator 10 movesand controls a movable barrier 12 which moves back and forth along apath indicated by direction arrow 1a of FIG. 1. The movable barrier 12when in a fully closed position fully blocks an opening 13 between fixedbarriers 14 and 16. In the fully closed position, the movable barrier 12fully blocks the opening 13 and thus restricts passage. In a fully openposition, the movable barrier 12 does not block the opening 13. Themovable barrier 12 is shown in FIGS. 1 and 2 between the fully open andfully closed positions. In the depicted embodiment, the movable barrier12 serves as a gate which controls passage based on inputs from devicessuch as induction loops 18a and 18b between a first region A and asecond region B demarcated by the fixed barriers 14 and 16, the opening13, and the movable barrier 12 along road surface 19 by vehicle 20 andother objects of movement such as pedestrians, animals, and other typevehicles as shown in FIG. 1.

The barrier operator 10 includes a station 21, and first and secondcables 22a and 22b, respectively, in the depicted embodiment of FIGS. 1and 2. The station 21 provides motive force to the first and secondcables 22a and 22b as described below. The first and second cables 22aand 22b are each attached at one end to opposite ends of the movablebarrier 12 at cable tensioners 24a and 24b, respectively, in thedepicted embodiment. The movable barrier 12 is supported by the fixedbarrier 14 through rollers 26, as illustrated in FIG. 1. The rollers 26are attached at fixed locations to the fixed barrier 14 and rollablysupport the movable barrier 12, allowing the movable barrier to movealong the directions indicated by the direction arrow 1a. The movablebarrier 12 is supported from below by wheels 28 attached at fixedlocations to the movable barrier for rolling along the ground or a track(not shown).

In other embodiments, the barrier operator 10 moves and controls othermovable barriers besides the movable barrier 12 of the depictedembodiment. These other movable barriers of other embodiments includedoors such as swinging, sliding, raising, lowering, rolling, or the likethat close openings for entrance and/or egress by persons, vehicles, orother objects into or out of buildings, other structures, restrictedareas, or pedestrian or vehicular traffic ways. Examples includevehicular traffic at entrances or exits to residential, commercial, orindustrial buildings or areas such as garages, loading docks, parkinglots, gated communities, or other secured areas. Further, movablebarriers include other types of gates including, but not limited to,swinging, sliding, raising, lowering, rolling, or the like that arestand-alone passage barriers or are portions of walls, barriers, orfence systems that control entrance and/or egress by persons, vehicles,or other objects, typically to complete or selectively close and openthe perimeters of defined areas. Another class of movable barriersincluded in further embodiments include, but are not limited to,louvers, shutters, cantilever devices, vertical pivot gates, horizontalslide-gates, swing-gates, lift-gates, draperies, blinds, shades, andwindows including skylights.

In addition to the first and second cables 22a and 22b, the station 21of the barrier operator 10 includes a platform and two supports that aresecurely attached to a support foundation. The station 21 of the barrieroperator 10 also has a drive system with drive system members includinga cable spool 30 as best shown in FIG. 3. The spool 30 serves as anoutput for the station 21 and receives and dispenses the first andsecond cables 22a and 22b. In the depicted embodiment, an electricalmotor 32 is the motive source that provides motive force for the barrieroperator 10. However, other embodiments involve other motive sourcessuch as hydraulic motors or compressed air, water, or other fluidturbines. The motor 32 provides its motive force to the spool 30 so thatthe spool turns either clockwise or counterclockwise indicated bydirection arrows 3a and 3b, respectively. The motor 32 provides motiveforce to the spool 30 through a series of drive system members elements.These drive system members include a motor pulley 34 coupled to arotating member such as a motor shaft (not pictured) of the motor 32. Abelt 36 is received on the motor pulley 34 and a gear box pulley 38. Thegear box pulley 38 is rotatably coupled to an input shaft 56 of a gearbox 40 and an output shaft 58 of the gear box is rotatably coupled tothe spool 30 (the input and output shafts 56 and 58 are shown in FIG.5).

The combination of the first and second cables 22a and 22b and the spool30 provide a vanging winch action for the barrier operator 10. Accordingto this vanging action, as the spool 30 turns in the clockwisedirection, indicated by direction arrow 3a of FIGS. 3 and 4, the firstcable 22a unwraps from the spool whereas the second cable 22b wrapsabout the spool. Thus, as the spool 30 rotates in the clockwisedirection 3a, the portion of the first cable 22a that is unwrapped andextending from the station 21 becomes longer and the unwrapped portionof the second cable 22b that extends from the station 21 becomesshorter. As best illustrated in FIGS. 1 and 2, as the unwrapped portionof the first cable 22a extending from the station 21 becomes longer, andthe unwrapped portion of the second cable 22b extending from the station21 becomes shorter, the movable barrier 12 moves toward the fully openposition. When the opening 13 is sufficiently unblocked by the movablebarrier, the vehicle 20 is allowed to pass through the opening.Alternatively if the spool 30 rotates in the counterclockwise directionindicated by direction arrow 3b of FIGS. 3 and 4, the unwrapped portionextending from the station 21 of the first cable 22a becomes shorter andthe unwrapped portion of the second cable 22b extending from the station21 becomes longer. As the unwrapped portions extending from the station21 of the first and second cables 22a and 22b become shorter and longerrespectively, the movable barrier 12 moves toward the fully closedposition. When the opening 13 is sufficiently blocked by the movablebarrier, the vehicle 20 is prevented from passing through the opening.

In other embodiments, the station 21 in the depicted embodiment isreplaced by other stations having various drive system members that arecoupled to a movable member of a motive source to provide motive forceto first and second flexible members such as the first and second cables22a and 22b attached to a movable barrier such as the movable barrier12. Similar to the depicted embodiment, these portions of the first andsecond flexible members extending from the station of another embodimentbecome shorter or longer depending upon the direction of force appliedto the drive system members of the station by the motive source and alsodepending upon the individual configuration of the various drive systemmembers. Further embodiments include a different type of output drivesystem member in place of the spool 30. Additional embodiments include aplurality of spools or other types of output drive system members. Othertypes of output drive system members include drum, capstan, tong,finger, or various projections, chain drive, grooves, tracks, or othersuch arrangements in which the first and second flexible members can bewrapped and unwrapped or otherwise furled and unfurled around oralongside. One or a plurality of motive sources is operably coupled tothe one or the plurality of output drive system members. Each of theplurality of output drive system members is coupled to one of the firstor second flexible members.

The motor 32 receives electrical power from a power system including abattery charger 42, batteries 44, an inverter 46, and a controller 48with processor 48a and memory 48b, as shown in FIG. 4. A sensor 50 iselectrically coupled to the controller 48 and operatively coupled tomagnets 52 mounted to the gear box pulley 38 for rotation therewith.Operation of the sensor 50 and the magnets 52 will be discussed below.

In the depicted embodiment, the spool 30 is made of 356 cast aluminum,has a 1 inch bore with a 1/4 inch keyway, and has a 7.483 inch diameter.The spool 30 further includes spaced-apart circumferentially extendingflanges 54a and 54b. The flanges 54a and 54b are 1/4 inch high to assistin retaining the first and second cables 22a and 22b wrapped on thespool 30. The distance between flanges 54a and 54b is 2.5 inches. In thedepicted embodiment, the first and second cables 22a and 22b areseparate individual cables and are each attached to the spool 30 bytheir one end so that slippage of the cables with respect to the spooldoes not occur. Attachment of the first and second cables 22a and 22b tothe spool 30 is done by cable terminations (not shown). The cableterminations are located on the inner surfaces of flanges 54a and 54b ofthe spool 30. In an alternative embodiment, the spool 30 has a thirdflange in the center of the spool located between the flanges 54a and54b to separate the first and second cables 22a and 22b on the spool. Inan alternative embodiment, a single cable may be used with its twolengthwise half lengths serving as the first and second cables 22a and22b. The central portion of the single cable may be passed through thecenter flange or attached to avoid slippage of the cable on the spool ifthe friction of the cable wrapped around the spool is insufficient.

An advantage of using the first and second cables 22a and 22b asseparate cables is that the distance between the flanges 54a and 54b canbe smaller than if a single cable is used. As a result, there is lessload applied to the gearbox 40 and the overall size of the barrieroperator 10 can be somewhat reduced. In the depicted embodiment, thefirst and second cables 22a and 22b are each two feet longer than themovable barrier 12. The spool 30 has a diameter sufficiently large suchthat for any position along the path of travel of the movable barrier12, the portions of the first and second cable 22a and 22b that arewrapped around the spool 30 are wrapped only in a single layer. Thefirst and second cables 22a and 22b have a 5/32 inch diameter and are7/19 stranded stainless steel. In alternative embodiments, the first andsecond cables 22a and 22b are other types of flexible members,including, but not limited to, ropes, chains, wire, string, filament,strand, cordage, and thread of metal, plastic, nylon, other syntheticmaterial, and other more naturally occurring materials, such as hemp andcotton, and other flexible members.

In the depicted embodiment, the first and second cables 22a and 22b areattached to the movable barrier 12 and the cable tensioners 24a and 24b,as described above. The cable tensioners 24a and 24b are adjustable toallow for adjustment of tension in the first and second cables 22a and22b. In the depicted embodiment, the cable tensioners 24a and 24b aremade of 356 cast aluminum. The cable tensioners 24a and 24b are fastenedto the movable barrier with two 5/16 inch bolts for each cabletensioner. In an alternative embodiment, tension adjustment of the firstand second cables 22a and 22b is accomplished by the spool 30 beingmanufactured in two halves that can be adjustably rotated in relation toone another and then locked in their relative rotational positions so asto then rotate as a unit to move the movable barrier 12.

Internal details of the gear box 40 are illustrated in FIG. 5. In thedepicted embodiment, the gear box 40 includes an input shaft 56 whichhas the gear box pulley 38 mounted thereon for rotation therewith. Thegear box 40 further includes an output shaft 58 that has the spool 30mounted thereon for rotation therewith. The input shaft 56 is coupled toa worm gear 62, rotatably supported at its ends by bearings 60a and 60b.A bearing 60c rotationally supports the output shaft 58. A worm wheel 64meshes with the worm 62 and is coupled to the output shaft 58 to supplyrotational drive thereto. The worm wheel 64 is rotatably supported by abearing 60c.

The gear box 40 derives its beneficial characteristics from the gearcoupling action between the worm 62 and the worm wheel 64. The worm 62and the worm wheel 64 are configured such that rotational forces appliedto the input shaft 56 are transferred to the output shaft 58 with thedesired torque and speed of rotation. In the depicted embodiment, ifrotational forces are applied to the input shaft 56 in either thecounterclockwise or clockwise directions, the rotational forces will betransmitted to the output shaft 58 in the same counterclockwise orclockwise directions. The application of rotational force from the inputshaft 56 to the output shaft 58 is the primary transmission mode of thegearbox 40.

The gearbox 40, however, has a secondary transmission mode. Thissecondary transmission mode occurs when rotational force is applied tothe output shaft 58 and transmitted back to the input shaft 56. Theconfiguration of the worm 62 and the worm wheel 64 allows rotationalforce applied to the output shaft 58 to be transmitted to the inputshaft 56 under a special condition. This special condition exists whenthe total force applied to the input shaft 56 by the rotor 32 is lessthan a certain threshold force. This threshold force is typically verysmall, but is at least somewhat greater than the rotational forcenecessary to overcome the resistance experienced at the input shaft 56resulting from the combined resistances of the gear box pulley 38, thebelt 36, the motor pulley 34, and the motor 32 when the motor isdeactivated and not receiving any electrical power from the powersystem.

Incorporating the concept of the threshold force into the design of thebarrier operator 10 increases the utility of the barrier operator. Inthe primary transmission mode, when forces applied to the input shaft 56of the gearbox 40 are greater than the threshold force, the gearboxeffectively opposes forces applied to the output shaft 48 of the gearboxby amplifying the forces applied to the input shaft. In the primarytransmission mode, the gearbox 40 either assists the motor 32 in movingthe movable barrier 12 or opposes movement of the movable barrier byforces directly applied to the movable barrier. In the secondarytransmission mode, when forces applied to the input shaft 56 of thegearbox 40 are less than the threshold force, the gearbox allows forcesdirectly applied to the movable barrier 12 to move the movable barrierwhich is helpful for cases such as emergencies or power failures.

In the depicted embodiment the worm 62 has a major diameter of 0.958inches, a thread depth of 0.225 inches, and a thread pitch of 0.237inches. The worm wheel has 38 teeth. The configuration of the worm 62and the worm wheel 64 results in a 19:1 gear ratio. Regarding thesecondary transmission mode for a case where the gearbox 40 is notcoupled to motor 32 and belt 36, a minimum of 1.3 foot pounds of torquemust be applied to the output shaft 58 of the gearbox at 70° F. withstandard gear oil for the input shaft 56 of the gearbox to rotate withno rotational force being applied to the input shaft. The 1.3 footpounds of torque and any drag of the motor 32 and belt 36 are allrelatively small and allow for manual movement of the movable barrier 12when the electrical power is not available to energize the motor 32.Other embodiments use gear boxes, exposed gears, a series or pair ofpulleys, various belt drives, sprockets, or other force converters aloneor in various combinations. These force converters may have higherminimum torque requirements while still allowing for manual movement ofthe movable barrier 12.

The ratio of the gear box pulley 38 to the motor pulley 34 is three toone. In the depicted embodiment the gear box pulley 38 has a diameter of3.3 inches. The gear box pulley 38 is made of 6061 T6 aluminum. The gearbox pulley 38 has a 3/4 inch bore with a 3/16 inch keyway and isdesigned to accommodate a standard six groove micro-V profile belt. Sixmagnets 52 are embedded in the gear box pulley 38 and are used indynamic and kinematic sensing and the analysis discussed below. Themotor pulley 34 has a 1.1 inch diameter and is made from a 12L14 leadoymaterial. The motor pulley 34 also has a standard six groove micro-Vprofile with a 5/8 inch diameter bore with a 3/16 inch keyway. The belt36 that couples the motor pulley 34 and the gear box pulley 38 has amicro-V profile. The depicted embodiment uses a micro-V profile beltmade by Gates Rubber having part number 240J6 for the belt 36.

A schematic drawing of FIG. 6 shows the functional relationships betweencomponents of the barrier operator 10 involved with power, control, andgeneration of motion. In the depicted embodiment, a power source 66,such as a conventional power line, provides 115 volt AC electricalpower. A power switch 68 controls supply of electrical power from thepower source 66. When permitted by the power switch 68, electrical powerflows from the power source 66 to the battery charger 42. The batterycharger 42 is connected to the batteries 44 and supplies chargingcurrent thereto. As will be described below, the batteries 44 providethe electrical power to operate the motor 32. Alternative embodimentsutilize batteries solely as standby power supplies for emergency back-uppurposes whereas under normal operation electrical power is supplied tothe motor 32 without the use of batteries.

In an alternative embodiment, a switch mode power supply receives theelectrical power from the power switch 68 to condition the electricalpower before it is received by the battery charger 42. In thealternative embodiment, the switch mode power supply allows the barrieroperator 10 to use electrical power with input voltages over broadranges including but not limited to a range between 70 and 290 volts,and 50 to 60 Hz AC. The battery charger 42 in the depicted embodimentoperates at 115 volts AC and 5 amps RMS to give an output appropriatefor charging a 24 volt battery system. Other embodiments includeadditional power supply equipment as appropriate for the size and typeof the movable barrier 12 and situation involved. Additional powersupply equipment includes smaller or larger capacity power supplies and,for backup purposes, larger and/or additional batteries.

In another alternate embodiment, solar photovoltaic panels are used todirectly charge the batteries 44. Since as shown in the depictedembodiment the inverter 46 of the gate operator 12 is electricallycoupled to the DC buss 70, the gate operator is readily adaptable toremote applications using solar panels.

The battery charger 42 is electrically coupled to the controller 48 andsends a signal to the controller upon a power failure. If power fails,the controller 48 initiates an energy conserving mode and executes oneof several possible power failure methods discussed below.

The batteries 44 in the depicted embodiment consist of two 12 voltbatteries each having a 7 amp-hour rating. The two batteries 44 areconnected in series to provide 24 volt, 7 amp-hour capacity. Thebatteries 44 provide electrical power to the controller 48 and theinverter 46 through a DC bus 70 having a positive and negative busvoltage. Other embodiments use batteries 44 of various voltages andamp-hour capacities.

The inverter 46 uses pulse width modulation to produce a constantvoltage three-phase AC electrical output with variable frequency. Foreach phase of the three-phase output, a pair of MOSFET transistorscontrols the electrical output. The pair of MOSFET transistors includesone MOSFET transistor connected to the positive bus voltage of the DCbus 70 and another MOSFET transistor connected to the negative busvoltage of the DC bus 70. By alternately switching between thepositively and negatively connected MOSFET transistors of each pair, analternating voltage is produced which results in the three-phase ACelectrical output. The MOSFET transistors are switched at a very highfrequency with varying time intervals to optimize the three-phase outputof the inverter 46 which is supplied to the motor 32.

In the depicted embodiment, the electrical output provided by theinverter 46 to the motor 32 is a three-phase AC having a nominal rootmean square (RMS) voltage between each phase of 16.75 volts at 60 Hz andabove. When the motor 32 is at rated full load, the inverter 46 suppliesapproximately 23 amps RMS of electrical current. However, the inverter46 is rated for a 60 amp RMS maximum output. The inverter 46 controlsthe frequency and the voltage of the three-phase output which rangesbetween 0-180 Hz and 0-20 volts. The controller 48 is electricallycoupled to the inverter 46 to provide control of the inverter 46including control of the frequency and the voltage of the three-phaseelectrical output to the motor 32. In alternative embodiments, theinverter 46 is supplied with DC electrical power having a voltagesmaller or greater than 24 volts including 12, 36, 48, 60, and 72 voltsor other voltages. In these alternative embodiments, the inverter 46supplies three-phase AC electrical power to the motor 32 having voltagelevels between each phase less than or equal to 65 volts RMS. Inalternative embodiments only frequency or voltage of the electricalpower supplied to the motor 32 is adjusted, but not both frequency andvoltage.

In the depicted embodiment, the motor 32 operates at approximately 16.75volts RMS, three-phase, four pole motor with a half horsepower maximumrated output. At rated full load, the motor 32 requires approximately 23amp RMS current. The motor 32 in the depicted embodiment uses 18 inchesof 10 gage wire for its leads. The rotational speed of the motor 32 isprimarily dependent upon the frequency and the voltage of the electricalpower supplied to the motor by the inverter 46. Thus, the inverter 46can control the rotational speed of the motor 32 by varying thefrequency and the voltage of supplied electrical power to the motor. Asstated, in the depicted embodiment, the frequency of the electricalpower supplied to the motor 32 ranges from 0 to 180 Hz. In otherembodiments, different motors of other voltage, pole, and horsepowerspecifications are used.

The controller 48 is electrically coupled to the sensor 50, tactilebuttons 72, external inputs 74, external outputs 76 and a thermistor 80or other temperature sensors. Based upon inputs from these varioussources, the controller 48 determines the proper frequency and voltagefor the electrical power supplied by the inverter 46 to the motor 32which results in a particular rotational speed of the motor and aresultant speed for the movable barrier 12. For instance in the depictedembodiment, when electrical power having a 60 Hz frequency is suppliedto the motor 32, the resultant speed of the movable barrier 12 is twelveinches/second. The direction that the motor 32 rotates is determined bythe phase relationship between the three phases of the electrical powersupplied by the inverter 46 to the motor 32. Thus, the controller 48 canchange the direction of movement of the movable barrier 12 by changingthe phase relationship between the three phases of the electrical powersupplied by the inverter 46 to the motor 32. Alternative embodimentsinclude adjustments of the frequency and/or the voltage of theelectrical power supplied to the motor 32 and/or adjusting transmissionratios of the drive system of the barrier operator 10 according toparticular torque requirements of an application.

The tactile buttons 72 include "open," "close," "stop," and "limit set"tactile buttons. Manual activation of the open, close or stop tactilebuttons 72 directs the controller 48 to move the movable barrier 12 tothe fully open position, the fully closed position, or to stop movementof the movable barrier. The limit set tactile buttons 72 are used incalibrating positions of the movable barrier as discussed below. Theexternal inputs 74 include key switches, card readers, radio signals,key punch pads, traffic detectors, photo eye outputs, pressure sensors,timer outputs, induction loops 18a and 18b, telephone entry devices,ultrasonic detectors, radar detectors and computer generated signals.The external outputs 76 include signals indicating barrier position,alarm signals, light indicators, control signals, and other computerinstruction signals. The manner in which the controller 48 uses thesevarious input sources to determine the frequency and the voltage of theelectrical power provided to the motor 32 will be discussed furtherbelow.

Inherent characteristics of the motor 32, the gear box 40, and thecontroller 48 enhance the amount of control that the barrier operator 10has in moving the movable barrier 12. One characteristic of the motor 32and the controller 48 is that they resist being forced to turn fasterthan the motor's three phase synchronous speed. The synchronous speed ofthe motor 32 is dependent upon the frequency and the voltage of theelectrical power supplied to the motor. Thus, if the controller 48 setsthe synchronous speed of the motor 32 at a rate lower than the currentspeed of the movable barrier 12, the motor will provide resistance in abraking fashion to slow down the speed of travel of the movable barrier.In addition, as discussed above, the gear box 40 resists forces appliedto the output shaft 58 of the gear box that are counter to forcesapplied to the input shaft 56 of the gear box. Thus, the gear box 40assists the motor 32 in accelerating and decelerating the movablebarrier 12. The combination of the motor 32 and the gear box 40 allowsthe barrier operator 10 to control heavy and fast moving gates in asmooth manner.

In the depicted embodiment, the sensor 50 and the magnets 52 (see FIGS.3 and 4) are configured to supply position information to the controller48. The magnets 52 are embedded around the perimeter of the gear boxpulley 38 with alternating north and south poles. The sensor 50 is anAllegro part No. 3422 and is positioned so that as the gear box pulley38 rotates, the magnets 52 pass by the sensor. The magnets 52 areoriented so that as the magnets pass by the sensor 50 with alternatingpole arrangements. The controller 48 using the sensor 50 determinesdirection, speed, as well as position of the movable barrier 12 bymethods known in the art. Position is determined by the controller 48counting and summing the pulses generated by the sensor 50. In adepicted embodiment, the combination of the controller 48, the sensor50, and magnets 52 are able to provide position information on themovable barrier 12 to a resolution of 0.21 inches. The controller 48determines position using a counter circuit that counts the electricalpulses induced each time one of the magnets 52 passes the sensor 50. Thecounter circuit compares its count relative to the fully open and fullyclosed positions to determine the present position of the movablebarrier 12. A method outlined in FIG. 7 is used on initial setup andalso after an extended power outage.

An alternative embodiment employs for position determination aphotoelectric transmitter and sensor and materials of various opticalcharacteristics affixed to a moving member such as the gear box pulley38. Another embodiment employs for position determination apotentiometer operatively coupled to a moving member such as the gearbox pulley 38. Electrical resistance of the potentiometer variesaccording to the position of the movable barrier 12.

A method for calibrating the position of the movable barrier 12 in thedepicted embodiment is illustrated in FIG. 7. The method first starts atstep 710 and goes to step 712 where the movable barrier 12 is movedeither manually or automatically to a position referred to as the "fullyopen position." In the fully open position, the opening 13 is unblockedand fully accessible. The method then goes to step 714 where the limitset tactile buttons 72 are either manually or automatically activated toconfirm to the controller 48 that the movable barrier 12 is in the fullyopened position. The method then goes to step 716 where the movablebarrier 12 is either manually or automatically moved to a positionreferred to as the "fully closed position." In the fully closedposition, the opening 13 is fully blocked by the movable barrier 12. Themethod then goes to step 718 where the limit set tactile buttons 72 areeither manually or automatically activated to confirm to the controller48 that the movable barrier 12 is in the fully closed position. Themethod then goes to step 720 where the method ends.

Both the fully open and fully closed positions indicated to thecontroller 48 are stored in the memory 48b of the controller (see FIG.4). Once the fully closed and fully opened positions are stored in thememory 48b of the controller 48, the controller is able to determinewith its processor 48a and counts of the counter circuit mentioned abovethe position of the movable barrier 12 to the resolution of 0.21 inches.The controller 48 also uses an internal clock 48c along with theposition information supplied by the sensor 50 to determine velocity,acceleration or deceleration, and rate of acceleration or decelerationof the movable barrier. The controller 48 also accounts for direction ofmovements since the movable barrier 12 is capable of moving in more thanone direction. Use of position and time data to determine velocity,acceleration, and rate of acceleration of objects is well known in thefield of kinematics.

In the depicted embodiment, the controller 48 executes a preprogrammedmethod to move the movable barrier 12. This method generally moves thegate from the fully open to the fully closed position, or from the fullyclosed position to the fully open position. As illustrated in FIG. 8,the method starts at step 810 and goes to step 812 where the frequencyof the electrical power supplied to the motor 32 is 0 Hz. This 0 Hzfrequency is the initial starting frequency for movement of the movablebarrier 12 from either the fully closed position to the fully openposition, or from the fully open position to the fully close position.

The method then goes to step 814 where the controller 48 changes theoutput of the inverter 46 so that the electrical power supplied to themotor 32 increases in frequency and voltage. The increase in frequencyand voltage in the depicted embodiment is linear allowing for a smoothincrease in speed of the movable barrier 12. In other embodiments, thecontroller 48 increases the frequency and voltage according topiece-wise linear or non-linear functions that are typically continuousfunctions of frequency of the electric power supplied by the inverter 46to the motor 32 versus the position of the movable barrier 12 to allowfor smooth acceleration. The controller 48 continues to increase thefrequency and voltage of the electrical power supplied from the inverter46 to the motor 32 until the frequency equals a predetermined frequencydesignated as the "travel frequency" in decision step 816. Differentpredetermined frequencies and voltages are assigned as the travelfrequency depending upon whether the situation calls for slower orfaster travel speeds of the movable barrier 12 than a typical travelspeed. In the depicted embodiment the typical travel frequency is 60 Hzwhich results in a travel speed for the movable barrier 12 of twelveinches per second. The decision step 816 branches under the NO conditionback to the step 814 until the frequency equals the travel frequencywherein decision step 816 branches under the YES condition to decisionstep 818.

In decision step 818 the controller 48 determines whether the movablebarrier 12 is near either the fully open position or fully closedposition. If the movable barrier 12 is near neither the fully openposition or the fully closed position, the decision step 818 branchesunder the NO condition back to decision step 818 where the movablebarrier continues to move at its predetermined travel speed. When thecontroller 48 determines that the movable barrier 12 is near either thefully open position or the fully closed position, the decision step 818branches under the YES condition to step 820 where the controllerlinearly decreases the frequency and the voltage allowing for a smoothdecrease in speed of the movable barrier as the movable barrierapproaches the fully open or closed position it is near and goes to step822. In other embodiments, the controller 48 decreases the frequency andthe voltage according to piece-wise linear or non-linear functions thatare typically continuous functions of the frequency of the electricpower supplied by the inverter 46 to the motor 32 versus the position ofthe movable barrier to allow for smooth deceleration.

In decision step 822, the controller 48 determines whether the frequencyequals a predetermined slow frequency. In the depicted embodiment theslow frequency is selected to be approximately 20 Hz which results intravel of the movable barrier of four inches per second. If not, thedecision step 822 branches under the NO condition back to step 820 wherethe frequency and the voltage is again decreased. In a depictedembodiment, the frequency and the voltage is decreased in step 820 in alinear fashion. If the frequency equals the slow frequency, the decisionstep 822 branches under the YES condition to decision step 824 where thecontroller 48 determines whether the movable barrier 12 has reachedeither the fully open position or the fully closed position. If not, themethod branches under the NO condition back to step 824 to allow themovable barrier 12 to move at the speed corresponding to the slowfrequency. If the movable barrier 12 is at either the fully openposition or the fully closed position, the method then branches underthe YES condition to step 826 where the controller 48 rapidly decreasesthe frequency and the voltage being supplied by the inverter 46 to themotor 32 until the frequency equals 0 Hz. The method then branches tostep 828 wherein the method ends.

In further embodiments, modifications of the method illustrated in FIG.8 are used by the controller 48 to move the movable barrier 12 frompositions other than fully open and fully closed positions or in othersituations. The controller 48 increases and decreases the frequency andthe voltage of the power supplied by the inverter 46 to the motor 32 ina linear manner. However, the predetermined travel speed of movablebarrier 32 may be decreased or increased, or the acceleration ordeceleration of the movable barrier 12 may be decreased or increasedbased on the particular situation involved and the position of themovable barrier 12 before movement starts. For instance, if the positionbefore movement of the movable barrier 12 is very near either the fullyopen position or the fully closed position, acceleration and travelspeed of the movable barrier 12 may be decreased. Whereas, if anyexternal input indicates that an unidentified vehicle is tailgating anauthorized vehicle, the values for the acceleration, the travel speedand subsequent deceleration of the movable barrier 12 may be increased.In other embodiments, the controller 48 adjusts both the frequency andthe voltage level of the electrical power supplied to the motor 32.

In alternative embodiments, if the open tactile buttons 72 is manuallyactivated when the barrier operator 10 is moving the movable barrier 12into the fully closed position, the controller 48 will rapidly decreasethe frequency and the voltage of electrical power supplied by theinverter 46 to the motor 32 until it reaches 0 Hz. The controller 48will then execute the method indicated in FIG. 8 to move the movablebarrier 12 to the fully open position.

If the stop tactile button 72 is manually activated, the controller 48will rapidly change the frequency and the voltage of the power suppliedby the inverter 46 to 0 Hz. Any close commands issued through the closetactile button 72 will initiate a stop function by the controller 48while the movable barrier 12 is moving open. Other embodimentsincorporate electrical signals received by the controller 48 from one ormore of the external inputs 74 to initiate operations similar to theopen, close, stop, and limit set operations initiated by the tactilebuttons 72.

Further embodiments include an automatic repositioning feature, with thecontroller 48 continuously monitoring the position of the movablebarrier 12. The repositioning feature counters unauthorized attempts tomove the movable barrier 12 or drifting of the barrier caused byenvironmental factors such as weather or positioning of the movablebarrier. Furthermore, the repositioning feature provides benefits of alock system, but does not require all the additional hardware that atypical lock system would require. If the movable barrier is movedwithout assistance by the motor 32, the sensor 50 will indicate a changein position at a time when the frequency of the power supplied by theinverter 46 to the motor will be at 0 Hz. If the movable barrier 12moves without the assistance of the motor 32, the controller 48 willmove the movable barrier back to the most recent position that themovable barrier was placed by the motor (i.e., the "original position").As stated, the controller 48 determines the position of the movablebarrier 12 within 0.21 inches for the depicted embodiment. Thus, if themovable barrier 12 is moved out of its original position by somethingother than the barrier operator 10 by an amount approximately greater orequal to 0.21 inches, the controller 48 will cause the inverter 46 toenergize the motor 32 with electrical power tailored to reposition themovable barrier at the original position and thus resist the externalforce being applied to the movable barrier. This tailored electricalpower in the depicted embodiment is approximately 3 volt RMS, 5 amp RMS,2 to 5 Hz, 3-phase electrical power having the proper voltage andfrequency to move the movable barrier back to its original position.Once the barrier operator 12 returns the movable barrier to the originalposition, the controller 48 causes the inverter 46 to stop supplyingelectrical power to the motor 32.

If the movable barrier 12 is moved out of the original position again bysomething other than the barrier operator 10, the barrier operator willagain return the movable barrier back to the original position once themovable barrier has traveled approximately greater than or equal to 0.21inches. The response time for the barrier operator 10 to start to returnthe movable barrier 12 back to the original position is approximately 50ms in the depicted embodiment. This repositioning feature essentiallyacts as a lock to keep the movable barrier 12 in a fixed positionagainst externally applied forces. A linear force of at leastapproximately 480 lbs. must be applied to the movable barrier 12 todefeat this lock feature by preventing the barrier operator 10 fromreturning the movable barrier to the original position.

Under a first energy conserving feature, the controller 48 senses theabsence of AC electrical power supplied to the charger 42 and enters oneof several modes including automatic open, lock open after next opencommand, stay closed except special override, or normal full functionuntil the batteries 44 are substantially discharged and followed by openand lock open. Additionally, the controller 48 continues to sense thevoltage levels on the DC bus 70. As the batteries 44 become partiallydischarged, the voltage level on the DC bus 70 will start to decrease ina manner well known in the art. Once the voltage level on the bus 70decreases to a particular level that indicates that the batteries 44have not been continually charged by the charger 42, such as during aprolonged power outage with the power source 66 not supplying power tothe battery charger 42, the controller 48 will go into a second energyconserving mode. In the second energy conserving mode, the controller 48adjusts the frequency and/or voltage level of the electrical powersupplied by the inverter 46 to the motor 32 so that the batteries 44 areless rapidly drained. As a result, a maximum limit of 30 Hz frequency isimposed on the electrical power supplied from the inverter 46. When thebatteries 44 are semi-discharged, the operating velocity with which thebarrier operator 10 moves the movable barrier 12 is limited. Also, inthe second energy conserving mode, the repositioning feature describedabove is inactivated when the batteries become substantially dischargedsuch as below 50% capacity which allows the movable barrier 12 to bemanually moved during power outages allowing access for medical andother emergency personnel that may otherwise be hindered from renderingaid. These first and second energy conserving modes are used eitherseparately or in combination in other embodiments. Alternativeembodiments of energy conserving modes also limit voltage either aloneor in combination with the frequency limit for power supplied by theinverter 46.

The controller 48 also uses external inputs 74 to modify how the barrieroperator 10 moves the movable barrier 12. For instance, the externalinputs 74 of the depicted embodiment include induction loops 18a and 18bthat sense the presence of a vehicle. In the depicted embodiment thebarrier operator 10 rapidly stops the movable barrier 12 from moving anyfurther to the fully open position once a vehicle starts to pass overthe second encountered induction loop in the vehicle's direction oftravel. For the case shown in FIG. 1, the second encountered inductionloop is the induction loop 18b based on the direction of travel of thevehicle 20 indicated by direction arrow 12a of FIG. 1. However, if thevehicle 20 is traveling in the opposite direction, indicated bydirection arrow 2b, the second encountered induction loop would be loop18a. The vehicle 20 starts to pass over the second encountered inductionloop (18b in this case) once the vehicle's front portion 20a crosses theline 2c and reaches the side indicated by cross 2d shown in FIG. 1. Oncethe vehicle's rear portion 20b is past the second encountered inductionloop (18b in this case) on the side of line 2e indicated by cross 2f ofFIG. 1, the gate operator 10 starts to move the movable barrier 12toward the fully closed position.

As a result, the gate operator 10 adjusts the length of travel of themovable barrier to accommodate for the speed of travel and the size ofthe vehicle 20. Another result is to discourage drivers of additionalvehicles from tailgating behind the vehicle 20 in order to pass throughthe opening 13 based on permission to pass granted to the vehicle 20. Inother embodiments the barrier operator 10 uses various other sensingmechanisms to determine the position of the vehicle 20 or other mobileobjects relative to the opening 13 and movable barrier 12 in place of orin addition to the induction loops 18a and 18b. Other embodimentsinclude quick stop features which prevent the movable barrier 12 fromhitting obstructions sensed by other external inputs 74 such as infraredand photoelectric sensors.

The controller 48 in one embodiment compares position and speeddeterminations based on both the frequency of the electrical powersupplied to the motor and data supplied by the sensor 50. The controller48 stops the barrier and issues a warning through one of the externaloutputs 76 such as alarm signals or light indicators if the position orvelocity based on frequency and sensor data are different. The warningis associated with conditions such as the motor 32 rotating faster thanthat predicted by the movement of the movable barrier 12 as indicated bythe sensor 50. When the motor 32 is rotating faster or slower than itshould be for the velocity of the movable barrier 12, a condition mayexist wherein something in the barrier operator 10 has broken or isslipping such as the belt 36. Because slip is high on startup, thecomparative circuit is not active for the first 1.5 seconds of eachstart.

The controller 48 also is programmed to use temperature data supplied bythe thermistor 80 to effectively use the motor 32 as a heater for theelectronics, batteries 44 and the gear box 40 of the gate operator 10.If the thermistor 80 senses that the ambient temperature near thecontroller has dropped below a first temperature threshold such as 30°F. and thus potentially resulting in impairment of operations of thecontroller, the batteries, or the gear box, the controller 48 willswitch the barrier operator 10 to a heater mode and cause the inverter46 to supply the motor 32 with electrical power having a frequency at ornear 0 Hz which does not result in rotation of the motor or movement ofthe movable barrier 12. With this power supplied, the motor 32 willproduce approximately 150 watts of heat. As this heat causes the ambienttemperature to rise past a second temperature threshold such as 35° F.,as sensed by the thermistor 80 in the area of the barrier operatorelectronics, the controller 48 signals the inverter 46 to stop supplyingelectrical power to the motor 32. In alternative embodiments, thethermistor 80 is replaced by a thermostat, or other temperature sensingdevice. If the controller 48 senses that power has failed, indicated bythe loss of AC electrical power to the battery charger 42, the inverter46 will not cause the motor 32 to act as a heater. Instead, thecontroller 48 will conserve remaining energy stored in the battery 44for moving the movable barrier 12. As a secondary benefit of the heatermode of operation of the barrier operator 10, the motor 32 offerspartial resistance to forces applied to the motor pulley 34 so that atleast approximately 80 pounds of linear force is required to move themovable barrier 12.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

What is claimed is:
 1. A barrier operator to move a movable barrier,other barrier operator comprising:a motive source having a movablemember; a stationary station including a drive system having an inputmember and an output member, the input member being coupled to themovable member of the motive source; and first and second flexiblemembers each having first and second end portions and an extendingportion extending a length from the station, the first end portions ofthe flexible members being operatively coupled to the movable barrier,and the second end portions of the flexible members being fixedlyattached to and wound around the output member of the station to acombined degree of at least two windings, the length of one of theextending portions of the first and second flexible members becomingshorter and the length of the other of the extending portions of thefirst and second flexible members becoming longer as the movable memberof the motive source moves to move the movable barrier.
 2. The barrieroperator of claim 1 wherein the motive source is one of the following:an electric motor, a hydraulic motor, or a compressed air turbine. 3.The barrier operator of claim 1 wherein the first and second flexiblemembers comprise first and second cables respectively.
 4. The barrieroperator of claim 1 wherein along midportion of the cable the first andsecond flexible members comprise a single cable attached to the outputdrive system member.
 5. The barrier operator of claim 1 wherein thefirst and second flexible members comprise one or more of the following:wire, rope, strand, string, chain, flexible tubing, or filament.
 6. Thebarrier operator of claim 1 wherein the first and second flexiblemembers are made of at least one of the following: metal, synthetics, ornatural non-metal material.
 7. The barrier operator of claim 1 whereinthe output drive system member of the station comprises a spool, andwherein the drive system of the station further comprises a gearboxoperatively coupled to the spool.
 8. The barrier operator of claim 1wherein the drive system of the station further comprises a gearboxoperatively coupled to a first pulley, wherein the first pulley isoperative coupled to a belt, wherein the belt is operatively coupled toa second pulley, and wherein the second pulley is operatively coupled tothe movable member of the motive source.
 9. The barrier operator ofclaim 1 wherein the drive system of the station includes a wormoperatively coupled to a worm wheel.
 10. The barrier operator of claim 1wherein the drive system of the station is configured to move themovable member of the motive source when the motive source isdeactivated and a force above a threshold force is applied to the outputdrive system member.
 11. A barrier operator to move a barrier, thebarrier operator comprising:a spool with a surface; first and secondflexible members each having first and second end portions and wrappedand unwrapped portions between the first and second end portions, thewrapped portions of the first and second flexible members having acombined fixed length wrapped around the surface of the spool of atleast two full windings and the unwrap portions of the first and secondflexible members each having a variable length extended from the spool,the first end portions of the first and second flexible members beingoperatively coupled to the barrier, the second end portions of the firstand second flexible members being affixed to the spool; a stationarydrive system having an output shaft operatively coupled to the spool andan input member; and a stationary motive source having a movable member,the movable member being operatively coupled to the input member. 12.The barrier operator of claim 11 wherein the motive source is one of thefollowing: an electric motor, a hydraulic motor, or a compressed fluidturbine.
 13. The barrier operator of claim 11 wherein the first andsecond flexible members comprise first and second cables respectively.14. The barrier operator of claim 11 wherein the drive system of thestation includes a worm operatively coupled to a worm wheel.
 15. Thebarrier operator of claim 11 wherein the motive source comprises anelectric motor powered by three phase alternating electric current,wherein the three phase alternating electric current has voltagedifferences between any two of the three phases no greater than 65 voltsroot mean square.
 16. The barrier operator of claim 11 wherein thewrapped lengths of the first and second flexible members sum to a totalwrapped length and the unwrapped lengths of the first and secondflexible members sum to a total unwrapped length, and wherein the totalwrapped length and the total unwrapped length being constant lengths.17. A barrier and operator system comprising:a movable barrier; anoutput member; first and second flexible members each having first andsecond end portions and furled and unfurled portions between the firstand second end portions, the furled portions of the first and secondflexible members having a combined fixed length furled at least two fullwindings about the output member and the unfurled portions of the firstand second flexible members each having a variable length extending fromthe output member, the first end portions of the first and secondflexible members being operatively coupled to the movable barrier, thesecond end portions of the first and second flexible members beingfixedly attached to the output member; and a stationary motive sourcehaving a movable member, the movable member being operatively coupled tothe output member.
 18. The system of claim 17 wherein the first andsecond flexible members comprise one or more of the following: cable,wire, rope, strand, string, chain, flexible tubing, or filament.
 19. Thesystem of claim 17, further comprising a drive system having an outputshaft operatively coupled to the output member and an input memberoperatively coupled to the movable member of the motive source.
 20. Thesystem of claim 17 wherein the motive source is one of the following: anelectric motor, a hydraulic motor, or a compressed fluid turbine. 21.The system of claim 17 wherein the output member comprises a spool. 22.The system of claim 17 wherein the output member comprises a flexiblemember receiver around which the first and second flexible members arewrapped and from which the first and second flexible members areunwrapped as the motive source moves the movable member of the motivesource to move the movable barrier.
 23. A barrier operator to move abarrier, the barrier operator comprising:a first and second outputmember, the first and second output member each having a surface; firstand second flexible members each having first and second end portionsand wrapped and unwrapped portions between the first and second endportions, the wrapped portions of the first and second flexible membershaving a combined fixed length wrapped around the surface of the firstand second output members of at least two full windings, and the unwrapportions of the first and second flexible members each having a variablelength extended from the first and second output members, respectively,the first end portions of the first and second flexible members beingoperatively coupled to the barrier, the second end portions of the firstand second flexible members being affixed to the first and second outputmembers, respectively; and at least one stationary motive source havinga movable member, the movable member being operatively coupled to atleast one of the first and second output members.
 24. The barrieroperator of claim 23 wherein the first and second flexible memberscomprise one or more of the following: cable, wire, rope, strand,string, flexible tubing, chain, or filament.
 25. The barrier operator ofclaim 23 further comprising at least one drive system each having anoutput shaft operatively coupled to at least one of the first and secondoutput members and an input member operatively coupled to the at leastone motive source.
 26. The barrier operator of claim 23 wherein the atleast one motive source is an electric motor.
 27. The barrier operatorof claim 23 wherein the first and second output members comprise spools.